1. Field of the Invention
The present invention relates generally to high pressure discharge lamps and more particularly to an improved strength ceramic arctube for use in a high pressure discharge lamp.
2. Description of Related Art
High pressure discharge lamps, which includes ceramic metal halide, high pressure sodium, and high pressure electrodeless lamps, are well-known and U.S. Pat. Nos. 5,140,227; 4,780,646; 4,409,517; and 3,363,133 are incorporated by reference. It is known in a high pressure metal halide discharge lamp to employ a ceramic arctube which includes a generally-cylindrical ceramic central body, a ceramic plug at each end of the central body, and a ceramic exhaust leg engaging each plug. See, e.g., Eur. Pat. App. EP 0 587 238 A1, the contents of which are incorporated by reference. It has been found that the join or joint between the exhaust leg and the plug is extremely weak, which may lead to failure at the leg, or a leak at the joint that may result in 0 eventual lamp failure.
There is a need for a reinforcement to strengthen the area where the exhaust leg engages the plug of a high pressure discharge lamp, to strengthen the leg and reduce the possibility of lamp failure.